Zinc oxide is colorless, and because it absorbs UV light below 380 nm wavelengths it is used as a UV absorber. It is similarly known that zinc compounds have bactericidal and fungicidal properties. In textiles, for example, this effect has been described for the production of a bactericidal polyamide filament, U.S. Pat. No. 7,074,482, a bactericidal PET fiber, CN1800454, modified cotton, CN1687509, viscose, JP8060431, viscose, acrylic fibers, PVC fibers, CN1442518, fibers comprising thermoplastic matrix and zinc sulfide, EP1 560 953 (whose United States equivalents are U.S. Patent Application Publication Nos. 2010/047366A1 and 2006/208390A1).
JP 08-060431 A describes viscose (rayon) fibers having antibacterial, deodorizing properties. The antibacterial properties are achieved by mixing the viscose with ceramic complexes. The ceramic complexes are obtained from a mixture of a) magnesium oxide, b) quartzite or zinc oxide and c) hornblende, zeolite or calcium oxide, which is subsequently fired. However, the maximum possible fraction of antibacterially active ceramic complexes in the viscose is relatively low. The coagulation and regeneration of the cellulose in the course of the production of viscose fibers always takes place in acidic coagulation and regeneration baths.
DE 198 02 588 A1 ( whose United States equivalent is U.S. Pat. No. 6,514,609) provides luminescent fibers, more particularly luminescent cellulosic fibers obtainable by the viscose process or by the NMMO process. They contain inorganic luminophore pigments which, on stimulation with visible or ultraviolet radiation, preferably display a phosphorescent effect. Transition metal- or lanthanoid-doped zinc sulfides, oxides, oxysulfides, silicates or aluminates are mentioned specifically. Silver-doped zinc sulfides display blue fluorescence for example. However, transition elements or lanthanoid elements can bring about an autocatalyzed, strongly exothermic decomposition of the NMMO.
EP 0 043 325 A1 ( whose United States equivalent is U.S. Pat. No. 4,280,925) describes filter materials comprising cellulose ester material which contain zinc sulfide or zinc oxide. The filter materials can be used to filter heavy metal ions, such as silver, mercury, lead, copper or cadmium out of aqueous solutions. The cellulose esters mentioned are cellulose acetate, cellulose butyrate and cellulose propionate and also mixtures thereof.
Moldings, specifically fibers and filaments, with antibacterial or antifungal activity are disclosed in WO 2004/044284 A1( whose United States equivalents are United States Patent Application Publication Nos. 2010/047366A1 and US 2006/208390A1). The activity is achieved via a zinc sulfide content. The proportion of zinc sulfide ranges from 0.01% to 10% by weight, based on the weight of the polymeric material which forms the molding. Polymeric materials specifically mentioned are polyurethanes, polyesters, polyamides, acrylic polymers, polyolefins, cellulose or cellulose esters.
DE 44 26 966 A1 discloses a process for producing highly filled and oriented cellulosic fibers and films by a specific dry-wet spinning process. The fillers used are finely divided substances, for example metal powders or ceramic substances. The proportion of filler can be up to more than 500% by weight, based on the weight of the cellulose.
DE 10 2007 019 768 A1 ( whose United States equivalent is United States Patent Application Publication No. US 2010/124861) discloses a process for producing antibacterially additized cellulosic fibers of high whiteness. The fibers are produced by a lyocell process. The antibacterial performance is achieved through the addition of silver-containing nanoparticles.
The processes described all lead to moldings wherein the effect of the zinc compounds decreases greatly with the number of washes, and often textile processing is severely curtailed at high concentrations of zinc compounds.